Explosively driven stud unit

ABSTRACT

A cap, adapted to be rigidly mounted in the rear end of a driving tool barrel, is provided with an axial bore extending rearwardly therein most of the way through the cap, leaving a thin wall at the rear end of the bore. A cuplike piston has its rear end closed by the cap and is mounted on a rod, the rear end of which is mounted in the cap bore. The rod has a passage through it from its rear end, communicating with an explosive charge inside the piston. A primer is mounted in the rear end of the passage and is detonated when a firing pin bends the thin wall against it. This fires the explosive charge and causes the rod to break inside the piston and drive forward a stud mounted on the front end of the rod.

United States Patent Robert Temple Swissvale;

Ernest E. Temple, Murraysville, Pa. [21] App1.No. 869,535

[72] Inventors [22] Filed Oct. 27, 1969 [23] Division of Ser. No. 649,957, June 29, 1967,

Pat. No. 3,497,124.

[45] Patented Feb. 23, 1971 [73] Assignee Mine Safety Appliances Company Pittsburgh, Pa.

[541 iibrosivm DRIVEN STUD UNIT 2,166,041 7/1939 Cox 227/9 2,213,435 9/1940 TempleJr 227/9 2,316,112 4/1943 Temple, Jr 227/9 Primary Examiner-Granville Y. Custer, Jr. Attorney-Brown, Murray, Flick & Peckham ABSTRACT: A cap, adapted to be rigidly mounted in the rear end of a driving tool barrel, is provided with an axial bore extending rearwardly therein most of the way through the cap, leaving a thin wall at the rear end of the bore. A cuplike piston has its rear end closed by the cap and is mounted on a rod, the rear end of which is mounted in the cap bore. The rod has a passage through it from its rear end, communicating with an explosive charge inside the piston. A primer is mounted in the rear end of the passage and is detonated when a firing pin bends the thin wall against it. This fires the explosive charge and causes the rod to break inside the piston and drive forward a stud mounted on the front end of the rod.

EXPLQSIVELY DRIVEN STUD UNIT This application is a division of our copending application, Ser. No. 649,957, filed June 29, 1967, new Pat. No. 3,497,! 24, issued Feb. 24, 1970.

It is among the objects of this invention to provide a stud unit which is complete in itself, which is sealed against entrance of water, and in which a stud can be located different distances from the 'rear end of the unit.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a longitudinal section through the tool attached to a pad eye and containing our stud unit;

FIG. 2 is a cross section of the tool taken on the line 11-" of FIG. 1; and

FIG. 3 is a view similar to FIG. 1, but showing the tool immediately after firing.

Referring to the drawings, an object, such as a pad eye 1 through which a stud is who driven for fastening it to the side 2 of a sunken vessel that is to be raised, has an opening 3 encircled by an externally threaded cylindrical flange 4. This flange may be integral with the rest of the pad eye or be a projecting portion of a ring welded in the pad eye opening. The flange is designed to support and anchor one end of anextremely high-powered explosively actuated tool while the tool is being fired to drive a stud through the pad eye opening and into the vessel. Before the stud is driven the pad eye can be held in place by magnets if desired. v

The tool includes a metal sleeve 6 having an internal screw thread at its front end that can be screwed onto flange 4. The rear end of the sleeve is providedwith an internal annular shoulder 7 that may be formed from a flange ring 8 screwed into the sleeve. The barrel 9 of the toolis slidably mounted in this ring and extends rearwardly a short distance from it. The front end of the barrel is encircled by a shoulder 10 that may be formed by the rear end of a collar 11 screwed onto the barrel, with a sealing ring 12 between them. The barrel supports a bushing 13 that will fit in the pad eye opening. The bushing is fastened to the collar in a manner that is sufficient to keep the two connected together only until the tool is fired. Thus, the collar may be provided with an internal annular shoulder 14, through which a thin tubular projection 15 on the bushing extends, with the rear end of the projection flared out slightly to hold the bushing in place. A sealing ring 16 encircles the bushing and engages the inside of the collar. The front end of the collar may extend into the pad eye flange 4 and be encircled by a sealing ring 17 that engages that flange. This sealing ring also serves the purpose of frictionally connecting the barrel with the pad eye flange until sleeve 6 can be screwed onto the flange. The bushing 13 has a surface, such as a shoulder 18, that will engage an opposing surface or shoulder in the pad eye opening. The front end of the bushing is closed by an integral end wall 19. To prevent water from being trapped in front of shoulder i8 while the bushing is being inserted in the pad eye, the bushing is provided with a longitudinal groove 20 that connccts the shoulder with the front end of the bushing.

Slidably mounted in barrel 9 is a cuplike piston 21, the rear end of which normally is seated in a recess in the front of a stationary cap 22 encircled by a sealing'ring23. The cap is provided with an axial bore, in which, the rear end of a rod 24 is screwed. The rear end of the passage s closed and sealed by a thin wall integral with the cap, as the bore does not extend entirely through the cap. The rod also isscrewed into the front end of the piston, from which it extends forward through a spacer 25 slidably mounted on the rod. The rod bolts the piston tightly to the cap. A very short length of the front end of the rod is screwed into the enlarged rear end of a stud 26 that has a pointed front end. By changing the length of the rod and spacer, the velocity at which the stud strikes wall 2 can be varied. A primer cap 27 is mounted in a recess in a rear end of the rod and is connected by an axial passage 28 to radial passages 29 that open into the piston around the rod. The passages and piston are filled with an explosive powder 30. Although the inside of the barrel is supposed to be sealed against the entrance of water, nevertheless it is desirable to apply a sealant to the threads of rod 24 when they extend through the front end of the piston. Behind the piston cap 22 a breechblock 32 is screwed into the rear end of the barrel and supports a rearwardly extending tube 33, in which a firing pin 34 is slidably mounted. A portion of the pin is encircled by a coil spring 35 that urges the spring forward, but the pin normally is held in its retracted cocked position by a U-shape spacer 36 straddling the pin between the rear end of the tube and and a knob 37 on the rear end of the pin. The tool also may be fired electrically, ifdesired, in a well-known manner.

When spacer 36 is removed from the firing pin after the sleeve has been attached to flange 4, the spring will drive the pointed front end of the firing pin through a passage 38 in the breechblock and against-the back of cap 22, which will be bent forward far enough to fire the primer. This will ignite the powder, which will explode and build up sufficient pressure in piston 21 to break rod 24 in a reduced diameter area, whereupon the piston will be driven forward in the barrel behind spacer 25 and the stud. The spacer and stud will move forward together until the stud has penetratedthe solid front end of the bushing and the adjoining wall of the vessel and the head of the stud has come to rest in the bushing as shown in FIG. 3. This will securely fasten bushing 13 to the vessel wall 2 and clamp the pad eye between bushing shoulder 18 and the vessel. The pad eye is provided with several openings 3 and flanges 4, and driving tools can be connected to all of the flanges and flred at the same time. As the stud is driven forward, piston 21 willbe stopped by collar shoulder 14, The recoil produced by the explosion will drive the barrel backward in sleeve 6, causing collar shoulder 14 to straighten flexible bushing projection 15 and pull away from it. Due to the short threaded connection between the front end of the rod and the stud, the few threads will be stripped and the stud and rod will separate. Openings 39in the side of the sleeve will permit water to escape as collar 11 moves backward in it.

A shock absorber 41" is mounted between the shoulder 7 in the rear end of the sleeve and the shoulder 10 around the front end of the barrel. This shock absorber encircles the barrel. When the tool is fired, the shock absorber is crushed by the recoiling barrel and therefore absorbs the shock of the recoil and prevents the shoulders 7 and 10 from striking each other. Preferably, the shock absorber is a coil of metal tubing, in which the convolutions engage or nearly engage one another. Copper tubing is preferred. Whenthe barrel'recoils, the convolutions of the tubing will crush and absorb the energy of the recoil. The resistance of the shock absorber to crushing can be varied by changing the size of the tubing, its wall thickness or the metal from which it is made. When the convolutions of the uncrushed coil are close together, the coil is shorter than the distance between shoulder 7 and 10 in order to allow the barrel to move backward in the sleeve a short distance before being restrained by the shock absorber. This gives the stud a chance to become firmly fixed in wall 2 before the rearwardly moving barrel attempts to pull thesleeve and the pad eye away from the wall. In case the convolutions of the shock absorber coil are spaced apart an appreciable distance, the ends of the coil could engage both of the adjoining shoulders because the coil would not start to crush and exert an outward force on sleeve 6 until after the convolutions have been moved together, and by that time the stud would be securely embedded in wall 2.

After the tool has been fired, the sleeve can be unscrewed from the pad eye flange and the barrel can be pulled out of the front end of the sleeve to permit the crushed shock absorbing coil to be removed and replaced by a new one so that the tool can be reused. The coil is inexpensive and easy to make and install.

The thin bendable wall of cap 22 behind rod 24 makes it unnecessary to provide any sealing element there to keep water from reaching the powder in the rod. The primer can be mounted in the endof the rod before the rod is screwed into the cap, which not only keeps powder from escaping from the rear end of the rod but also forms a convenient way of inserting the primer in the cap bore. The powder in rod passage 28 insures that the detonated primer will ignite the powder charge, especially when a quick burning or flash powder is used in the passage, Without powder in that passage, the primer flash might not always reach the charge inside the piston. The sealing material between the piston and cap and between the rod and front end of the piston prevents water that may leak into the tool barrel from reaching the powder inside the piston. The importance of spacer 25 has already been mentioned.

We claim:

1. An underwater explosively driven stud unit, comprising a cap adapted to be rigidly mounted in the rear end of a driving tool barrel and provided with an axial bore extending rearwardly therein most of the way through the cap, the cap having an integral thin bendable wall closing the rear end of the bore, a rod tightly mounted in said bore and extending forward therefrom, a cuplike piston in front of said cap having an open rear end closed by the cap, the piston having an opening in its front end through which said rod extends, the piston being rigidly mounted on the rod, an explosive charge inside the piston around the rod, the rod being provided with a passage extending from its rear end forward into communication with said charge, a primer mounted in the rear end ofsaid passage substantially in engagement with said thin wall. and a stud having a rear end removably mounted on the front end of the rod and supported by it, said thin wall being adapted to be bent forward by a firing pin to detonate the primer. and the rod being provided inside the piston with a weakened area adapted to break when said charge is fired by the primer.

2. An underwater explosively driven stud unit according to claim 1, in which said passage is filled with explosive flash powder.

3. An explosively driven stud unit according to claim 1, including a spacer mounted on said rod between the stud and piston to locate the front end of the stud a predetermined distance from the piston, the front end of the rod being threaded and projecting ahead of the spacer, and the rear end of the stud being provided with a threaded opening and screwed onto the rod and against the spacer. 

1. An underwater explosively driven stud unit, comprising a cap adapted to be rigidly mounted in the rear end of a driving tool barrel and provided with an axial bore extending rearwardly therein most of the way through the cap, the cap having an integral thin bendable wall closing the rear end of the bore, a rod tightly mounted in said bore and extending forward therefrom, a cuplike piston in front of said cap having an open rear end closed by the cap, the piston having an opening in its front end through which said rod extends, the piston being rigidly mounted on the rod, an explosive charge inside the piston around the rod, the rod being provided with a passage extending from its rear end forward into communication with said charge, a primer mounted in the rear end of said passage substantially in engagement with said thin wall, and a stud having a rear end removably mounted on the front end of the rod and supported by it, said thin wall being adapted to be bent forward by a firing pin to detonate the primer, and the rod being provided inside the piston with a weakened area adapted to break when said charge is fired by the primer.
 2. An underwater explosively driven stud unit according to claim 1, in which said passage is filled with explosive flash powder.
 3. An explosively driven stud unit according to claim 1, including a spacer mounted on said rod between the stud and piston to locate the front end of the stud a predetermined distance from the piston, the front end of the rod being threaded and projecting ahead of the spacer, and the rear end of the stud being provided with a threaded opening and screwed onto the rod and against the spacer. 